#include <bits/stdc++.h>
//#pragma GCC optimize("unroll-loops")

using namespace std;
typedef long long ll;
typedef pair<ll,ll> pll;
int Time(){
    return chrono::steady_clock::now().time_since_epoch().count();
}
random_device rd;
mt19937_64 gen(rd());
int uniform_rand(int l, int r){
    uniform_int_distribution<ll> rnd(l,r);
    return rnd(gen);
}
const int NMAX=2e4+5,MMAX=1e5+5;
ifstream fin("cuplaj.in");
ofstream fout("cuplaj.out");
vector<ll> edg[NMAX*4+MMAX*2];
struct edge{
    ll v,cap;
}edges[NMAX];
ll s,t,ans,dist[NMAX],ptr[NMAX];
ll flux(ll u,ll f){
    if(f==0 || u==t) return f;
    for(ll& i=ptr[u];i<edg[u].size();i++){
        ll it=edg[u][i];
        if(dist[edges[it].v]==dist[u]+1 && edges[it].cap){
            ll augment=flux(edges[it].v,min(f,edges[it].cap));
            if(augment==0) continue;
            edges[it].cap-=augment;
            edges[it^1].cap+=augment;
            return augment;
        }
    }
    return 0;
}
int main()
{
    ios_base::sync_with_stdio(false); fin.tie(0);
    ll n,m,e,id=0;
    fin>>n>>m>>e;
    for(ll i=0;i<e;i++){
        ll u,v;
        fin>>u>>v;
        v+=n;
        edges[id]={v,1};
        edges[id^1]={u,0};
        edg[u].push_back(id), edg[v].push_back(id^1);
        id+=2;
    }
    for(ll i=1;i<=n;i++){
        edges[id]={i,1};
        edges[id^1]={0,0};
        edg[0].push_back(id), edg[i].push_back(id^1);
        id+=2;
    }
    for(ll i=n+1;i<=n+m;i++){
        edges[id]={n+m+1,1};
        edges[id^1]={i,0};
        edg[i].push_back(id), edg[n+m+1].push_back(id^1);
        id+=2;
    }
    s=0,t=n+m+1;
    while(1){
        for(ll i=0;i<=n+m+1;i++) dist[i]=-1,ptr[i]=0;
        queue<ll> q;
        q.push(s),dist[s]=0;
        while(!q.empty()){
            for(auto it : edg[q.front()]){
                if(dist[edges[it].v]==-1 && edges[it].cap>0){
                    dist[edges[it].v]=dist[q.front()]+1;
                    q.push(edges[it].v);
                }
            }
            q.pop();
        }
        if(dist[t]==-1) break;
        ll f=0;
        while((f=flux(s,INT_MAX))>0)
            ans+=f;
    }
    fout<<ans<<'\n';
    for(ll i=1;i<=n;i++){
        for(auto it : edg[i]){
            if(edges[it].cap==0 && edges[it].v>n && edges[it].v<=n+m){
                fout<<i<<' '<<edges[it].v-n<<'\n';
            }
        }
    }
    return 0;
}